Enhancement of photo-fenton-like degradation of orange II by MnO2/NiO nanocomposite with the synergistic effect from bisulfite.

Abstract To improve the efficiency of traditional advanced oxidation processes (AOPs), a novel photo-assisted heterogeneous Fenton-like process was proposed and verified by experiments. Under visible light, NaHSO 3 and transition metal composite oxide MnO 2 /NiO were tested together for degradation of orange II (OII). MnO 2 /NiO nanocomposites were prepared by a hydrothermal method using different nickel oxide to manganese oxide ratios and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Ultraviolet–vis (UV–vis) diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The best MnO 2 /NiO nanocomposite (Ni:Mn = 1:2) which was designated as Ni-Mn-3 showed the best OII removal efficiency of about 92.8% among the various MnO 2 /NiO nanocomposites of different Ni:Mn ratios. Moreover, the best catalyst, Ni-Mn-3 also showed good stability and recovery performance for degrading OII. The degradation ability of Ni-Mn-3 decreased no more than 10% after three times of repeated tests, which makes it more competitive in practical industrial applications than other heterogeneous Fenton-like catalysts. Graphical abstract Image 1 Highlights • New photo-assisted heterogeneous Fenton-like process was used with MnO 2 /NiO catalysts. • Key novelty was the use of NaHSO 3 to activate MnO 2 /NiO under visible light. • The MnO 2 /NiO (Ni:Mn = 1:2) showed the best Orange II removal efficiency of about 92.8%. • 1Ni:2Mn oxide showed good stability and recycling performance for degrading Orang II. [ABSTRACT FROM AUTHOR]